This invention relates generally to a method and apparatus for providing an audio signal to a listener, and more particularly to a method and apparatus for generating an audio signal within the ear canal of a listener so that the listener may receive the audio signal without the audio signal causing any crosstalk or echoing problems with a related microphone, and for ensuring that the audio signal is not heard by anyone other than the intended listener.
In recent years, the use of cellular phones, and other small headset receiver/microphone units has increased. When receiving an audio signal from a speaker thereof positioned outside a listener""s ear, an audio signal is generated in the speaker and directed towards the listener""s ear. However, if this generated audio signal is played at a level sufficient to allow a listener to hear it, an echo or crosstalk at an associated transmitter microphone may result since the generated audio signal can be received by the transmit microphone, and be inadvertently transmitted thereby back to the source.
In an attempt to eliminate, or at least reduce this echo problem, prior art apparatuses have reduced to a minimum a transmit gain for the microphone while the headset speaker is generating the audio signal by way of complicated digital signal processing schemes. Other attempts at eliminating or reducing this echo problem have included controlling the geometries and positions of the microphone and the speaker relative to each other. However, because a speaker in such a headset is driven to produce a sound pattern whose direction is not easily controlled, these attempts at reducing echo and crosstalk have been less than satisfactory.
Therefore, it would be beneficial to provide an apparatus including a speaker/earpiece and microphone which allow a user to hear information and retransmit information, respectively, while reducing the echo and crosstalk therebetween to an acceptable level.
Accordingly, it is an object of the invention to provide an improved method and apparatus for receiving and reproducing an audio signal.
Another object of the invention is to provide an improved method and apparatus for allowing a user to hear an audio signal received via a wireless transmission and reducing the amount of echo and crosstalk produced in an associated microphone.
A further object of the invention is to provide an improved method and apparatus for providing an audio signal to a listener which reduces the possibility of the audio signal being listened to by anyone other than the intended listener.
Still another object of the invention is to provide an improved method and apparatus for generating an audio signal in a listener""s ear canal, thereby reducing echo, and ensuring privacy of the audio signal.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification and drawings.
Generally speaking, in accordance with the invention, an improved method and apparatus for providing an audio signal to a listener is provided. An audio signal is provided to a user via an earpiece which generates this audio signal within the ear canal of the listener. The audio signal is generated using a concentric transducer scheme to generate different ultrasonic waveforms focused within the listener""s ear canal. The concentric ultrasonic beams are directed into the ear canal where the nature of the ear detects the audible modulation between the concentric ultrasonic beams. One of the transducers is designed as part of a stable oscillator and feeds a sample of its signal to a circuit that modulates this oscillation by an audio information signal and provides only the lower difference-frequency signal thereof to a transducer driver. This transducer driver then powers the second transducer of the concentric transducer pair to generate the modulation noted above. The audio information signal may be provided to the earpiece via a wire from an external receiver unit, or alternatively, from an internally based receiver unit.
Therefore, in accordance with the invention, the audio signal is generated within the ear canal of a listener, thereby reducing echo and crosstalk between the generated audio signal, and any signal being transmitted through an associated microphone, and further ensures the security of the audio signal listened to by the user.
The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others, and the apparatus embodying features of construction, combinations of elements and arrangement of parts which are adopted to effect such steps, all as exemplified in the following detailed disclosure, and the scope of the invention will be indicated in the claims.